Various different types of linear actuators are available in the market, and there is one type of linear actuators, wherein an electric motor and an outer pipe are installed on a base, and a lead screw is installed onto the base and electrically driven and rotated by the electric motor. In addition, the lead screw includes a telescopic pipe installed at the exterior of the lead screw, and an outer pipe sheathed on the exterior of the telescopic pipe, and an end of the outer pipe is fixed to the base, such that the telescopic pipe can be driven by the electric motor to move the lead screw linearly back and forth in an axial direction with respect to the outer pipe. However, users cannot know whether or not the telescopic pipe has moved to the end of the stroke when the linear actuator is operated, but the telescopic pipe is operated continuously even when the telescopic pipe has moved to the end of the stroke, and thus the linear actuator may be damaged easily.
To overcome the aforementioned problem, related manufacturers have developed a linear actuator with a stroke-restricting device, wherein a switch is installed at both ends of the outer pipe separately, and a block protruded from an end of the telescopic pipe is provided for retracting the telescopic pipe inwardly or moving the telescopic pipe outwardly to a limit position, and the block will touch each switch to stop driving the electric motor, so as to achieve the effect of controlling and operating the linear actuator to the limit of the stroke.
However, although the aforementioned structure can achieve the effect of controlling and operating the linear actuator to the limit of the stroke, yet the switch is installed inside the outer pipe, so that the outer pipe must come with a special space for accommodating each switch, and thus not only causing a higher level of difficulty for manufacturing the outer pipe, but also incurring a higher material cost. Furthermore, each switch is installed at both ends in the outer pipe separately, such that most parts of the linear actuator must be removed for the maintenance and repair of a damaged component, and thus making the maintenance and repair work more difficult and inconvenient. For linear actuators with a special shape or specification, the aforementioned conventional stroke-restricting device cannot be installed or applied. Obviously, the conventional stroke-restricting device requires improvements.